2005 Silverado problem with audio source switch

[Bikerjw]

This is an intermittent annoyance.
AND, does not happen every day, when it does happen will not happen again that day.
Only happens when there is a CD in the radio/CD player
(single CD radio with a cassette also)

Cycling through the 'source' button on the left side of the steering wheel, when it gets to the CD player the radio goes black. Station presets are maintained but the clock resets to 12:00

Has anyone heard of this and know what the problem is?
The vehicle is still under warranty and I plan on taking it in - but in past experiences it is tough to fix something if they cannot reproduce the problem.